Secondary palate

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Secondary palate
Pig snout sagittal cut.jpg
A sagittal section of a pig's (Sus sp.) snout showing the secondary palate with pronounced palatine raphe.
Details
Identifiers
Latin Palatum secundarium,
palatum definitivum
TE palate_by_E5.4.1.1.4.0.5 E5.4.1.1.4.0.5
Anatomical terminology

The secondary palate is an anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates.

Contents

In human embryology, it refers to that portion of the hard palate that is formed by the growth of the two palatine shelves medially and their mutual fusion in the midline. It forms the majority of the adult palate and meets the primary palate at the incisive foramen.

Clinical significance

Secondary palate development begins in the sixth week of pregnancy and can lead to cleft palate when development goes awry.

There are three major mechanisms known to cause this failure:

  1. Growth retardation — Palatal shelves do not grow enough to meet each other.
  2. Mechanical obstruction — Improper mouth size, or abnormal anatomical structures in the embryonic mouth prevent fully grown shelves from meeting each other.
  3. Midline epithelial dysfunction (MED) [1] - The surface mucosa of embryonic shelves is impaired, which causes a failure of palatal fusion.

Evolution

The secondary palate is thought to have a significant role in the development of some warm-blooded animals. The separation of the mouth from the nasal cavity also allowed chewing and breathing to occur at the same time. Early creatures with secondary palates include crocodilians (who are cold-blooded), and cynodonts and a few others among the therapsids, known from the fossil record in the mid-Permian. Mammals inherited our hard palates from the cynodonts.

Related Research Articles

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<span class="mw-page-title-main">Cleft lip and cleft palate</span> Birth defect of the palate and upper lip

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<span class="mw-page-title-main">Soft palate</span> Flexible part of maxilla

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<span class="mw-page-title-main">Palatine bone</span> Bone of the facial skeleton

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<span class="mw-page-title-main">Hard palate</span> Solid part of maxilla

The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans the alveolar arch formed by the alveolar process that holds the upper teeth.

<i>Galesaurus</i> Extinct genus of cynodonts from the Triassic of South Africa

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<span class="mw-page-title-main">Incisive foramen</span> Opening of the incisive canals on the hard palate immediately behind the incisor teeth

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<span class="mw-page-title-main">Secondary palate development</span>

The development of the secondary palate commences in the sixth week of human embryonic development. It is characterised by the formation of two palatal shelves on the maxillary prominences, the elevation of these shelves to a horizontal position, and then a process of palatal fusion between the horizontal shelves. The shelves will also fuse anteriorly upon the primary palate, with the incisive foramen being the landmark between the primary palate and secondary palate. This forms what is known as the roof of the mouth, or the hard palate.

<span class="mw-page-title-main">Pierre Robin sequence</span> Medical condition

Pierre Robin sequence is a congenital defect observed in humans which is characterized by facial abnormalities. The three main features are micrognathia, which causes glossoptosis, which in turn causes breathing problems due to obstruction of the upper airway. A wide, U-shaped cleft palate is commonly also present. PRS is not merely a syndrome, but rather it is a sequence—a series of specific developmental malformations which can be attributed to a single cause.

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<span class="mw-page-title-main">Human nose</span> Feature of the human face

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<span class="mw-page-title-main">Premaxilla</span> Cranial bones at the very tip of the upper jaw of many animals

The premaxilla is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals has been usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or os premaxillare, intermaxillary bone or os intermaxillare, and Goethe's bone.

<span class="mw-page-title-main">Frontonasal dysplasia</span> Medical condition

Frontonasal dysplasia (FND) is a congenital malformation of the midface. For the diagnosis of FND, a patient should present at least two of the following characteristics: hypertelorism, a wide nasal root, vertical midline cleft of the nose and/or upper lip, cleft of the wings of the nose, malformed nasal tip, encephalocele or V-shaped hair pattern on the forehead. The cause of FND remains unknown. FND seems to be sporadic (random) and multiple environmental factors are suggested as possible causes for the syndrome. However, in some families multiple cases of FND were reported, which suggests a genetic cause of FND.

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<span class="mw-page-title-main">Jaw abnormality</span> Medical condition

A jaw abnormality is a disorder in the formation, shape and/or size of the jaw. In general abnormalities arise within the jaw when there is a disturbance or fault in the fusion of the mandibular processes. The mandible in particular has the most differential typical growth anomalies than any other bone in the human skeleton. This is due to variants in the complex symmetrical growth pattern which formulates the mandible.

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<span class="mw-page-title-main">Hypernasal speech</span> Abnormal vocal sound due to excess airflow through the nose during speech

Hypernasal speech is a disorder that causes abnormal resonance in a human's voice due to increased airflow through the nose during speech. It is caused by an open nasal cavity resulting from an incomplete closure of the soft palate and/or velopharyngeal sphincter. In normal speech, nasality is referred to as nasalization and is a linguistic category that can apply to vowels or consonants in a specific language. The primary underlying physical variable determining the degree of nasality in normal speech is the opening and closing of a velopharyngeal passageway between the oral vocal tract and the nasal vocal tract. In the normal vocal tract anatomy, this opening is controlled by lowering and raising the velum or soft palate, to open or close, respectively, the velopharyngeal passageway.

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In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.

Cleft lip and clip palate is an "umbrella term" for a heterogeneous collection of orofacial clefts. It includes clefting of the upper lip, the maxillary alveolus, and the hard or soft palate, in various combinations. The anatomic combinations include:

References

  1. Dudas, Marek; Li, Wai-Yee; Kim, Jieun; Yang, Alex; Kaartinen, Vesa (March 2007). "Palatal fusion – Where do the midline cells go?: A review on cleft palate, a major human birth defect". Acta Histochemica. 109 (1): 1–14. doi:10.1016/j.acthis.2006.05.009. PMID   16962647.